Internally illuminated sign

ABSTRACT

An internally illuminated sign in which a luminaire mounted on the border or periphery of the sign uniformly illuminates the face and/or faces of the sign thereby eliminating any necessity for providing human access to the interior of the sign for maintenance and relamping.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 646,917 filed on Jan. 28, 1991, now U.S. Pat. No. 5,188,453, byHolophane Company, Inc. The applications have, at all times relevanthereto, been commonly owned.

FIELD OF THE INVENTION

This invention relates generally to illuminated signs and morespecifically to an illuminated sign having internal illumination.

BACKGROUND OF THE INVENTION

Internally illuminated signs have one or more translucent faces ormessage areas which are illuminated by lamps mounted inside the sign.While internally illuminated signs are often preferred over externallylighted signs, internally lighted signs of the prior art have been muchmore expensive to construct than externally lighted signs, especiallywhen the sign is large. Internally illuminated signs are usually lightedwith fluorescent lamps, although in some instances the light ininternally illuminated signs is provided by mercury vapor or metalhalide lamps. The translucent faces of the sign can be either rigid orflexible. Small rigid translucent faced internally illuminated signsoften have hinged faces in order to provide access to the lamps formaintenance and relamping, whereas, large internally illuminated signsnormally utilize flex faces and are built up to thirty-six inches deepto allow a person to enter the sign through the side and thereby provideaccess to the lamps for maintenance and relamping. In order to provide asign having sufficient depth to allow human access, it is necessary forsign manufacturers to build a framework structure for the sign whichadds significantly to the cost of the sign. In externally lighted signs,aluminum extrusions which are relatively inexpensive are often used asthe outer framing. However, since aluminum extrusions have a practicalcross-section limit of about fifteen inches, the depth of the largeinternally illuminated signs precludes sign manufacturers from usingaluminum extrusions for the outside structure of the signs which requirehuman access, thereby greatly increasing construction costs ofinternally illuminated signs of the prior art. In addition, ininternally illuminated signs of the prior art, there has been difficultyin achieving the desired uniformity of luminance across the full area ofthe sign face, since there is a tendency for the portion of the face ofthe sign adjacent the lamp to be much brighter than the rest of the signface.

BRIEF SUMMARY OF THE INVENTION

This invention relates to an internally illuminated sign in which theneed for human access into the interior of the sign for maintenance andrelamping is eliminated thereby eliminating the need for a deep sign andthe higher costs associated with such sign construction. The presentinvention provides an internally illuminated sign in which a luminairemounted on the border or periphery of the sign uniformly illuminates thefaces of the sign. A significant feature of the present invention isuniformly illuminating the face or faces of the sign. As noted above, ininternally illuminated signs of the prior art, there was a tendency forthe portions of the sign face adjacent the lamps to be brighter than therest of the sign face resulting in an uneven and undesirabledistribution of light across the sign face.

The luminaire mounted on the border and internally illuminating thefaces of the internally illuminated sign includes an aluminum reflectorfor distributing light in a fan-shaped pattern laterally along the signand parallel to the sign faces, and a refractor which intercepts thelight and directs the light to provide a uniform luminance on the signfaces while at the same time blocking direct source light frompenetrating the sides of the refractor and producing a bright spot on aportion of the sign face adjacent the luminaire.

These and other features and aspects of the invention, as well as itsvarious benefits, will be made more clear in the detailed description ofthe invention which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing the interior of an internallyilluminated sign constructed in accordance with an embodiment of thepresent invention, in which a number of luminaires mounted on the borderof the sign uniformly illuminate the faces of the sign;

FIG. 2 is a frontal sectional view of the interior of one of theluminaires mounted on the border of the sign as pictured in FIG. 1,illustrating a luminaire reflector and the fan-shaped lateraldistribution of light reflecting therefrom;

FIG. 3 is a side sectional view of the interior of one of the luminairesmounted on the border of the sign as pictured in FIG. 1 and FIG. 2,illustrating the parabolic contoured bottom of the luminaire reflectorof FIG. 2 directing light rays straight up;

FIG. 4 is a frontal sectional view of the interior of one of theluminaires mounted on the border of the sign as pictured in FIG. 1,illustrating a luminaire refractor which through the use of prismsprovides an even distribution of light onto the inside surfaces of thesign faces;

FIG. 5 is a side sectional view of the interior of the luminaire aspictured in FIG. 3, illustrating the action of horizontal reflectingprisms located on the outside surfaces of the sides of the luminairerefractor adjacent the faces of the sign blocking and reflecting most ofthe direct light that would normally produce excessive luminance on thesign face;

FIG. 6 is a top sectional view of the side sectional view of theinterior of the luminaire pictured in FIG. 5, illustrating the lightpattern resulting from the action of vertical biasing prisms located onthe inside surface of the sides of the refractor;

FIG. 7 is a perspective view of an alternative embodiment of theinterior of the luminaires mounted on the border of the sign as picturedin FIG. 1, shown with the reflector having fluted sections verticallydisposed in the luminaire housing to redirect light on the signtranslucent faces;

FIG. 8 is a perspective and partially fragmented view of an alternativeembodiment of the luminaires mounted on the border of the sign aspictured in FIG. 1, shown including layers of adjustable translucentpanels for obtaining the correct of light blockage;

FIG. 9 is a perspective view of an alternative embodiment of theluminaires mounted on the border of the sign as pictured in FIG. 1,shown including vertically disposed and spatially separated perforatedmetal plates for use in reducing the brightness on the sign translucentfaces on the luminaire; and

FIG. 10 is a perspective view of an alternative embodiment of theluminaires mounted on the border of the sign as pictured in FIG. 1,shown including vertically disposed and spatially separated louvers forreducing "bright spots' on the sign translucent faces.

DESCRIPTION OF THE INVENTION

Referring to FIG. 1, there is shown in an embodiment of the presentinvention a sectional view of the interior of an internally illuminatedsign generally identified by the reference numeral 10 in which a numberof luminaires 12 mounted at a lower periphery or border 14 of the sign10 are adapted to provide a light distribution pattern generallyidentified by the reference numeral 16 to uniformly illuminate the faces18 of the sign 10. Each of the luminaires 12 is mounted in such a mannerthat its lamp or light source 20 is positioned below the translucentfaces 18 of the sign 10 and has an easily openable housing 11 whichextends down below the sign 10. The housing 11 may be opened in anynumber of ways, for instance, it may be pivotally mounted about a hinge13 and secured in a closed position by a latch 15, so that it may beopened to provide easy access to the interior of the luminaire formaintenance and relamping.

With the luminaires 12 mounted at the lower border 14 of the sign 10,the luminaires can be opened for maintenance and relamping without theneed for a deep sign to provide human access. Since the presentinvention eliminates the necessity of having a deep sign, thetranslucent faces 18 of the sign 10 can be spaced less than 15 inchesapart from one another and the outer structure of the sign can be madeout of aluminum extrusion or other relatively inexpensive construction.While FIG. 1 illustrates the utilization of a number of luminaires, itshould be apparent that the number of luminaires necessary is dependenton the size of the sign. Also, while in the embodiment of the inventionillustrated in FIG. 1, the sign has two translucent faces the sameprinciples of the present invention apply whether the sign has one ormore translucent faces. Furthermore, while in the embodiment of theinvention illustrated in the drawings, the luminaire is positioned atthe bottom of the sign it is equally satisfactory to position theluminaires anywhere along the border of the sign such as at the top orthe sides for instance.

Referring to FIG. 2, there is shown a frontal sectional view of theinterior of one of the luminaires 12 mounted on the border of the sign10, having therein the lamp or light source 20, a reflector 22, made ofaluminum or the like, positioned below the light source 20 and arefractor 24. As illustrated in FIG. 2, the reflector 22 is designed toreflect the light from the light source 20 in a fan-shaped pattern,generally identified by the reference numeral 26, laterally across asegment of the sign 10.

In FIG. 3 there is shown a side sectional view of the interior of theluminaire 12 of FIG. 2, illustrating the parabolic contoured bottom 28of the reflector 22 reflecting light rays from the light source 20 upthrough the top 30 of the refractor 24 in a light distribution patterngenerally identified by the reference numeral 32, parallel to the face18 of the sign 10.

With reference to FIG. 7, there is further shown an additionalembodiment of reflector 22 having fluted sections 33 vertically disposedin housing 11 to redirect light and reduce the brightness of "hot spots"or "bright spots" on the sign translucent faces 18 near luminaires 12.

FIG. 4 is a frontal sectional view of the interior of the luminaire 12in FIG. 2, illustrating the manner in which the refractor 24, by meansof prisms as shown in FIG. 4, directs light from the light source 20into a uniform pattern of light, generally identified by the referencenumeral 34, onto the inside surfaces of the sign faces 18.

Referring now to FIG. 5, there is shown again the side sectional view ofthe interior of the luminaire 12 as pictured in FIG. 3, now illustratinga light pattern, generally identified by the reference numeral 36,formed by the action of horizontal reflecting prisms 37, as shown inFIGS. 3 and 5 on the outside surfaces of the sides 38 of the luminairerefractor 24 adjacent the translucent faces 18 of the sign 10 blockingand/or reflecting and redirecting most of the direct light from thelight source 20 and minimizing light penetration through the sides 38 ofthe refractor 24 that would normally produce excessive luminance on thesign translucent faces 18.

All or a portion of these reflecting prisms 37 may be coated to assistin blocking and redirecting the light rays. Reflecting prisms 37 may beselectively coated with ceramic paints or other known heat-tolerantpaints which can provide similar blocking performance. In the preferredembodiment, as shown in FIGS. 3-5, prisms 37 are selectively rearsurface metalized via spraying or other known deposition techniques toobtain the required light blocking and/or light redirection. The coatingprocess is applied to prisms 37 at a selected angle depending on theprismatic structure in order to partially coat the prisms. The uncoatedareas of the prismatic structure allow light to penetrate and berefracted. The coated parts of the prismatic structure allow light to beredirected back to the reflector 22, allow light to be directed towardsome other useful part of the luminaire 12 or allow light to be blocked.

In an alternative embodiment as shown in FIG. 8, layers of translucentmaterial 39 such as white diffusing panels, for example, may be used toblock light near the luminaire 12, thereby reducing the brightness ofthe sign. Layering the translucent material provides a means ofadjusting the correct amount of light blockage. Those skilled in the artwill thus recognize that multiple layers will block more light, wherenecessary.

In yet another alternative embodiment as shown in FIG. 9, verticallydisposed and spacially separated perforated metal plates 41 may also beused to reduce the brightness on the sign translucent faces 18 near theluminaire. Still further, in yet another alternative embodiment as shownin FIG. 10, vertically disposed and spacially separated louvers 43 mayalso be used to reduce "bright spots" on sign translucent faces 18.Louvers 43 may also be coated preferably with a heat resistant materialto improve their efficiency in blocking light.

Referring now to FIG. 6, which is a top sectional view of the sidesectional view of the interior of the luminaire 12 pictured in FIG. 5,there is illustrated the action of vertical biasing prisms 33, as shownin FIG. 6, located on the inside surface of the sides 38 of therefractor 24 to reduce penetration of light through the refractor sides38 and redirect light from the light source 20 laterally along thetranslucent faces 18 of the sign 10.

The action of the vertical biasing prisms located on the inside surfaceof the sides 38 of the refractor 24 cooperate with the horizontalreflecting prisms 37 on the outside surfaces of luminaire refractor 24to effectively avoid the appearance of a bright spot on the portion ofthe sign translucent face 18 adjacent the light source 20.

The horizontal reflecting prisms 37 on the outside of the sides 38 ofthe refractor 24 are positioned so their axes are coincident with thelight rays inside the glass. Since there is normally some rounding oneach peak and valley of the prisms 37, this rounding will allow light togo directly through and cause brightness on the face of the sign were itnot for the action of the vertical biasing prisms 39. Since each peakand valley of the vertical biasing prisms 39 will also be rounded and toillustrate the point, assuming for example, the rounding of each prismto be approximately 10%, the inside vertical prisms coupled with theoutside horizontal prisms will reduce the amount of the light goingdirectly through the refractor to 10% times 10% or 1%.

Another function of the internal biasing prisms 39 is to allow as muchgreater acceptance angle for the outside reflecting prisms 37. Withlight going directly into a reflecting prism, there is only a range of±3 degrees for total internal reflection. If the source is larger thanthis ±3 degrees, than the prism will start to "leak." Accordingly, withthe action of the internal vertical biasing prisms 39 biasing the lightin a direction parallel to the reflecting prism path 37, the angle ofthe light with respect to the normal of the reflecting surface becomesmuch greater and therefore total reflection occurs from a much largersource.

From the foregoing, it can be seen that there has been provided by thesubject invention a new and improved internally illuminated sign inwhich a luminaire mounted at the lower border or periphery of a signutilizes a reflector to distribute light in a fan-shaped patternlaterally along the sign and parallel to the face of the sign, and arefractor to intercept light and redirect it to provide a uniformluminance on the sign face while at the same time blocking direct sourcelight from penetrating the sides of the refractor and producing hotspots on the sign face.

It should be obvious that although a preferred embodiment of theinvention has been described, it is possible to make changes to certainspecific details of the assembly without departing from the spirit andscope of the invention.

What is claimed is:
 1. For use in a sign having at least two spatiallyseparated faces adapted to be illuminated from light radiated into theinterior of said sign between said spatially separated faces, said atleast two spatially separated faces including at least one translucentface, a luminaire, comprising:a housing mountable on the periphery ofsaid sign; illumination means disposed in said housing for providinglight directly into the region between said spatially separated faces; apair of spatially separated fluted reflector panels disposed in saidhousing for dispersing said light in a fan shaped pattern in a directionaway from said interior into the region between said spatially separatedfaces; and a refractor attached to said housing for directing light fromsaid reflector panels into a uniform pattern of light to uniformlyilluminate said spatially separated faces and for eliminating brightspots on said at least one translucent face.
 2. For use in a sign havingat least two spatially separated faces adapted to be illuminated fromlight radiated into the interior of said sign between said spatiallyseparated faces, said at least two spatially separated faces includingat least one translucent face, a luminaire, comprising:a housingmountable on the periphery of said sign; illumination means disposed insaid housing for providing light directly into the region between saidspatially separated faces; a fluted reflector panel disposed in saidhousing for dispersing said light in a fan shaped pattern in a directionaway from said interior into the region between said spatially separatedfaces; and a refractor attached to said housing for directing light fromsaid reflector panels into a uniform pattern of light to uniformlyilluminate said spatially separated faces and for eliminating brightspots on said at least one translucent face.
 3. In a sign having atleast two spatially separated faces adapted to be illuminated from lightradiated into the interior of said sign between said spatially separatedfaces, said at least two spatially separated faces including at leastone translucent face, the improvement comprising:a luminaire mountableon the periphery of said sign having means for providing light in theregion between said spatially separated faces, means for eliminatingbright spots on said at least one translucent face adjacent saidluminaire, said elimination means comprising a number of translucentpanels, and means for dispersing light in the interior of said signbetween said spatially separated faces to uniformly illuminate at leastone translucent face.
 4. A luminaire as in claim 3, wherein said meansfor dispersing light comprises a fluted reflector panel.
 5. A luminaireas in claim 3, wherein said means for dispersing light comprises a pairof spatially separated fluted reflector panels.
 6. A luminaire as inclaim 3, wherein said number of translucent panels is variable.
 7. Aluminaire as in claim 3, wherein said number of translucent panels aredisposed parallel to said at least one translucent face.
 8. A luminaireas in claim 3, wherein said number of translucent panels are layered,said number of panels being variable to achieve a desired amount oflight blocking.